Gridded bathymetry (5m) of the bank environment of Galvez Bank, and 2 small nearby banks
S. Galvez Bank (~ 3 nmi south of Galvez) and 11-mile Reef (~ 5 nmi north of Galvez, 11 nmi west of Guam),
Territory of Guam, USA. These netCDF and ASCII grids includes multibeam bathymetry from the
Reson 8101 multibeam sonar aboard the NOAA Ship Oscar E. Sette collected as of May 2010 by the NOAA Coral
Reef Ecosystem Division in depths between 10 and 300 meters.

Purpose:

These netCDF and ASCII grids were created using data gathered from multibeam soundings for use as a
planning and reference document. The data are also being used for benthic habitat
mapping, for locating Essential Fish Habitat, and for studying geologic features of
the area. Refer to supplemental information for description of instrument and survey.

Supplemental_Information:

Multibeam data were collected aboard the NOAA Ship Oscar Elton Sette, a 224' (68 m) United States
National Oceanographic and Atmospheric Administration research ship. The NOAA Ship
Sette's survey sensors included a 240-kHz pole-mounted Reson 8101ER sonar, which provides
bathymetry and imagery data, a TSS/Applanix POS/MV Model 320, which measures position,velocity, attitude and heading, and a Seabird SBE19 CTD used to measure sound velocity profiles.

These data are not to be used for navigation purposes.
Please acknowledge NOAA and the Joint Institute for Marine and Atmospheric Research (JIMAR)
University of Hawaii as the sources of this information.

netCDF file created using the Generic
Mapping Tools (GMT) and ArcGIS ASCII file, both created in a
LINUX environment

Data_Quality_Information:

Attribute_Accuracy:

Attribute_Accuracy_Report:

Data are collected for resource management
and research purposes and are tested for internal consistency; however,
no effort is made to compare these data to external references or to
other published data.

Logical_Consistency_Report:

These data are believed to be logically consistent
though no tests were performed

Multibeam swath files are acquired in the Generic Sensor Format (GSF) and
are edited on a swath by swath basis using SAIC's SABER editing software.
The edited swath files are then combined into a Pure File Magic (PFM) format
in SABER and area based editing is performed. The edited PFM is then exported
as X,Y,Z. The resulting X,Y,Z data are then gridded using xyz2grd, a Generic
Mapping Tools (GMT) algorithm that converts an ASCII or binary table to a netCDF
grid file format. GMT is an open source collection of tools for manipulating
geographic data sets. Grid nodes with more than one value are set to the average
value and unconstrained nodes are set to NaN. Finally, the netCDF grid is
clipped at a depth that minimizes data gaps for the specified grid cell size and
then converted to an ArcGIS ASCII file format using LINUX/UNIX commands in
combination with GMT. Additional information about GMT can be found at:
www.soest.hawaii.edu/gmt and additional information about the multibeam data
processing is recorded in the cruise metadata.

Process_Date: 20110331

Spatial_Data_Organization_Information:

Direct_Spatial_Reference_Method: Raster

Spatial_Reference_Information:

Horizontal_Coordinate_System_Definition:

Planar:

Grid_Coordinate_System:

Grid_Coordinate_System_Name: Universal Transverse Mercator

Universal_Transverse_Mercator:

UTM_Zone_Number: 55

Transverse_Mercator:

Scale_Factor_at_Central_Meridian: .9996

Longitude_of_Central_Meridian: -147

Latitude_of_Projection_Origin: 0

False_Easting: 500000

False_Northing: 0

Planar_Coordinate_Information:

Planar_Coordinate_Encoding_Method: Row and Column

Coordinate_Representation:

Abscissa_Resolution: 5

Ordinate_Resolution: 5

Planar_Distance_Units: meters

Geodetic_Model:

Horizontal_Datum_Name: D_WGS_1984

Ellipsoid_Name: WGS_1984

Semi-major_Axis: 6378137.000000

Denominator_of_Flattening_Ratio: 298.257224

Vertical_Coordinate_System_Definition:

Depth_System_Definition:

Depth_Datum_Name: mean lower low water

Depth_Resolution: 0.01

Depth_Distance_Units: meters

Depth_Encoding_Method: Attribute Values

Entity_and_Attribute_Information:

Overview_Description:

Entity_and_Attribute_Overview:

Depth values are real values based on the average of the
soundings that fell within the extracted grid cells. The number of
soundings per grid cell range from >1000 soundings in shallow depths
to as few as 20 soundings in deeper areas. A total error budget for
this survey has not been developed. Therefore, the accuracy of depth
measurements should be considered to be within 1 meter.

These data are not to be used for navigational purposes.
NOAA makes no warranty regarding these data, expressed or implied, nor
does the fact of distribution constitute such a warranty. NOAA cannot
assume liability for any damages caused by any errors or omissions in
these data, nor as a result of the failure of these data to function
on a particular system.